Question

In a laminar flow over plate the thickness of hydrodynamic boundary layer is 2 mm. What will be the thickness of thermal boundary layer? Fluid properties $\mu =4\times {10}^{-4}kg/m-s,k=0.664W/mK,Pr=2.54$

• A. 2.54 mm
• B. 1.68 mm
• C. 1.43 mm
• D. 5.08 mm

Answer 1

The correct option is C 1.43 mm

$\frac{{\delta }_t}{\delta }=\frac{1}{1.0246}(Pr{)}^{-1/3}$
$\frac{{\delta }_t}{2}=\frac{1}{1.0246}(2.54{)}^{-1/3}$
${\delta }_t=1.43mm$